How to Pronounce the AI /aɪ/ Diphthong
The AI in time is a diphthong. Diphthongs are made of two sounds, so that means each diphthong has a starting position and an ending position. You should feel your articulators move as you say the sound.
Pure vowels vs. diphthongs
When a vowel is part of a diphthong, sometimes it doesn’t sound as pure as it does when it is by itself. The AI diphthong is made up of these two vowels, /a/ and /ɪ/. The first sound, /a/, is not used in the standard American accent. And the final sound is /ɪ/, like in bit. But listen to how the IH sounds when it is in the diphthong: AI. AI. It doesn’t sound like the pure IH vowel. The jaw is a little more closed and the tongue is a little higher in the final sound of AI than when the IH vowel is said by itself. You don’t need to focus any of your time on why the IH vowel sounds different in a diphthong, just know that as long as your mouth position is correct as you glide through the diphthong, then you’ll be making the correct sound.
Stressed AI in time
Watch my mouth position as I say the word time. At the beginning of the vowel, the jaw is dropped low. The tongue is also low, and the tongue tip touches the back of the bottom front teeth. Then as I progress to the second sound of the diphthong, the jaw closes, and the tongue arches up closer to the roof of the mouth. The tongue tip stays behind the bottom front teeth.
When AI is in a stressed syllable, the pitch of my voice glides up and then down. AI. Time.
But in an unstressed syllable, the AI vowel is pronounced at a lower pitch with a flatter shape and it is quicker. AI. AI.
It is common to simplify or reduce the pronunciation of diphthongs when they are in an unstressed syllable. Native speakers simplify the pronunciation so that the unstressed syllable can be said quicker than the stressed syllables.
Stressed AI vs. Unstressed AI
Here is a close up of what AI looks like in an unstressed syllable, like in the word necktie.
The stressed AI is in the top pictures, and the unstressed AI is in the bottom pictures. Notice the difference in jaw opening between the stressed and unstressed positions. When AI is in an unstressed syllable, the jaw does not open as much compared to the stressed syllable. The jaw is also opened less at the end of the diphthong in the unstressed syllable.
Stressed AI. Time. Unstressed AI. Necktie.
Practice Words and Sentences
Here are some practice words and sentences:
Try. AI. Try.
I’ll try to do it.
Gigantic. AI. Gigantic.
That elephant is gigantic!
Vitamin. AI. Vitamin.
I take vitamins every day.
Outside. AI. Outside.
My cat loves to go outside.
Triathlon. AI. Triathlon.
My dream is to complete a triathlon.
Alibi. Ai. Alibi.
She has a strong alibi.
Thanks so much for watching! And let me know how I can help you with pronunciation of the American English diphthong vowels!